Blood returning to the heart from the peripheral circulation and the lungs generally flows into the atrial chambers of the heart and then to the ventricular chambers, which pump the blood back out of the heart. During ventricular contraction, the atrio-ventricular valves between the atria and ventricles (i.e., the tricuspid and mitral valves) close to prevent backflow or regurgitation of blood from the ventricles back to the atria. The closure of these valves, along with the aortic and pulmonary valves, maintains the uni-directional flow of blood through the cardiovascular system. Disease of the valvular apparatus can result in valve dysfunction, in which some fraction of the ventricular blood regurgitates back into the atrial chambers.
Traditional treatment of heart valve stenosis or regurgitation, such as mitral or tricuspid regurgitation, involves an open-heart surgical procedure to replace or repair the valve. Current accepted treatments of the mitral and tricuspid valves include: valvuloplasty, in which the affected leaflets are remodeled to perform normally; repair of the chordae tendineae (also referred to herein as “chords”) and/or papillary muscle attachments; and surgical insertion of an “annuloplasty” ring, which involves suturing a flexible support ring over the annulus to constrict the radial dimension. Other surgical techniques to treat heart valve dysfunction include fastening (or stapling) the valve leaflets to each other or to other regions of the valve annulus to improve valve function.
Additionally, advances have been made in the techniques and tools used in minimally invasive heart surgery. For example, to avoid open heart procedures (which may require that the patient's heart be stopped and that the patient be put on a bypass machine), devices and methods have been developed for performing heart surgery via intravascular or percutaneous access. Some challenges in performing these procedures include positioning the treatment catheters or other devices at a desired location for performing the procedure, and deploying an implant or other treatment device at a desired location.
When the minimally invasive heart surgery to be performed is valve repair (e.g., mitral valve repair), part of the valve anatomy itself may be used to overcome certain positioning challenges that may arise during the valve repair procedure. Specifically, the subannular space, such as the subannular groove, which is described in further detail below, may be used for catheter and device placement. See, e.g., U.S. patent application Ser. No. 10/461,043 (issued as U.S. Pat. No. 6,986,775); Ser. No. 10/656,797 (published as US 2005/0055087 A1); Ser. No. 10/741,130 (published as US 2004/0193191 A1); Ser. No. 10/776,682 (published as US 2005/0107810 A1); Ser. No. 10/792,681 (published as US 2004/0243227 A1); Ser. No. 10/901,019 (published as US 2005/0065550 A1); Ser. No. 10/901,555 (published as US 2006/0058817 A1); Ser. No. 10/901,554 (published as US 2005/0107812 A1); Ser. No. 10/901,455 (published as US 2006/0025750 A1); and Ser. No. 10/901,444 (published as US 2006/0025784 A1), all of which are incorporated herein by reference in their entirety. As described in some of these applications, a catheter may be advanced to, and seated in, the subannular groove and may be used to accurately position one or more devices, tools, etc. (e.g., implants and/or other catheters) for valve treatment. In this way, difficulty in accessing the valve annulus (e.g., as a result of error in implant placement and/or entanglement with chordae tendineae, as discussed below) may be reduced.
As mentioned briefly above, the heart includes chordae tendineae, which are tendons in the left and right ventricles, some of which connect the heart's papillary muscles to its mitral and tricuspid valves. These chords help to hold the mitral and tricuspid valve leaflets in position, preventing the valves from moving into the atria when the ventricles contract. Primary or first-order chords attach papillary muscles to the free edges of the valve leaflets, secondary or second-order chords attach papillary muscles to the ventricular surfaces of the valve leaflets, and tertiary or third-order chords connect the ventricular walls to the undersurfaces of the posterolateral leaflets. In some cases, the chords (especially the tertiary or third-order chords) may present obstacles to a heart valve repair procedure. As an example, they may obstruct the advancement of a catheter within a subvalvular space during a heart valve repair procedure (e.g., the catheter may become entangled in the chords).
In view of the above, it would be desirable, whether in a minimally invasive procedure or another type of procedure, to enhance the deliverability of devices, implants, and/or tools to valvular tissue during a heart valve repair procedure. For example, it would be desirable to reduce the extent of interference presented by chords during a heart valve repair procedure. It would also be desirable to provide additional devices, methods, and kits for visualizing one or more regions of a heart (and/or implants within one or more regions of a heart). Furthermore, it would be desirable to provide devices, methods, and kits for assessing the accessibility of a heart region, and/or for accessing a heart region.